Pagoda SL Group
W113 Pagoda SL Group => Drive train, fuel, suspension, steering & brakes => Topic started by: jaymanek on June 06, 2011, 09:36:03
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Hi Gentlemen,
I have a 1969 280 SL Euro.
As you may have read I have just rebuilt the head on my car and was feeling very proud of myself until yesterday.
The car was running great after I did the head.. last week i decided to set everything up... idle air/fuel, ignition timing etc.
Yesterday the car started misfiring badly whilst cruising, if i dip the clutch the car would cut out. However the problem dissapears as quickly as it comes... Upon restarting each time the car would run fine again for some time... then the problem would reappear...
I have set the timing to 30deg with vac hose connected as in my haynes manual. Initially I had set it to 30 with hose disconnected as per instructions on here, but that must be for US cars or maybe earlier cars as my car did not like that setting one bit.
Something to note is that before I set the timing up, it was running well but was in the region of 50 degrees at 3000rpm... The car seems to run stronger the further the ditributor is turned anti clockwise...
Dwell angle is still around 33, where I set it last year... I realise it should be 38 but i struggled to get it any closer and seemed to run fine...
Apologies if the above doesnt make sense, but im not that used to older ignition systems!
Any ideas please?
p.s. most of the system is new - Distributor cap, rotor arm, condensor, points, plugs & leads... the only old parts are the coil and ballast resistor as far as im aware.
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Well I changed the coil last night with a new Beru replacement and set the timing to 35 degrees at 3000 rpm instead of 30... went for a decent test drive and no problems... holding my breath but i have a feeling it will come back to bite me!
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It does sound like an ignition problem to me, although once I had forgotten to tighten down the bracket that holds the accellerator linkage across the engine. I had tightened the bolts by hand and there was a slight amount of play. Well that caused very similar symptoms as when the ignition is not right. So you may want to just double check all the connections in your linkages and make sure they're tight.
P.s. I have also found that when spark plugs have fouled because of whatever cause, this can render them bad, and cleaning does not help, at which point they have to be replaced. So putting in a fresh set of plugs even if the current ones are not old and look ok, may just save a lot of other diagnostics and trial and error. If they are not the problem, you can always put the old ones back in and save the new ones for the next service.
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Thanks...
Now that you mention it.... I also adjusted all the throttle linkages last week, could there be a relationship here?
I printed off and followed the instructions on here, and got the car idling perfectly - the previous owner had set the linkages so at idle neither the fuel distributor nor the air intake were quite in the closed position... a common thing from reading posts on here...
The issue I have in this department now is that the accelerator pedal seems to stick slightly at the beginning when i depress - i guess i need to lubricate my air intake flap.
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Hello Jaymanek,
The sticky accelerator pedal could be caused by the venturi flap sticking in it's bore. Adjust the small slotted screw on the venturi a bit to keep this from happening if this is the case.
Otherwise the linkage rod from the cross over rod to the linkage pivot on the intake manifold may need adjusted so that it is not resting on its top dead center.
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Thanks, Ill do that tonight and report back.
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Jaymanek,
Hope you found your problem. Though not entirely applicable here, there is a general penchant to blame fuel systems for electrical issues...
...which is why an old tongue in cheek service manual I had once for a 1960s Austin said that "Carburetor is a French word meaning 'It's the electrical system, stupid'!"
The same book also had, as part of the points adjustment, a directive to remove the rotor and place in your front pocket. When the instructions then called for reassembly, it said, "Now, remove the rotor from your front pocket..."
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Well ive done several trips now and all seems well..
I changed:
- Coil pack - Standard Beru Replacement
- Adjusted dwell angle to 38 deg, it was at 33 deg previously as I couldnt get it spot on before.
- adjusted timing to 35 deg at 3000rpm (vac connected) as opposed to 30 deg in the book
- New distributor cap (old one was recent from the dealer anyway)
- New rotor arm (old one was recent from the dealer anyway)
I think the most likely real cause was the coil pack and maybe the timing.
Car pulls really well now with no hesitation or spluttering...
Lets hope it lasts!
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Sometimes the distributor isn't indexed properly. The drive gear below the distributor can be turned so that the rotor will point to number one on the cap when the crank is at TDC and both valves are closed on number one cylinder. If the drive gear is out one tooth, the marks on the front balancer will probably be off as well. The car will appear to idle well at 40 degrees when it's reality it's at 5 degrees BTDC ( just an example, yours may be some other number ) You can set the distributor anywhere you want and as long as it's time the engine will run. Number one will strobe at a different place on the crank unless everything is indexed correctly.
You can index the distributor or live with it.
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Thats an interesting thought Benz Dr.
I will look into this although im reluctant to change anything now that its running good and starting on the button from cold or warm..
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Some great advice is "don't fix it if it isn't broken".
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Some great advice is "don't fix it if it isn't broken".
If I looked at everything that way I'd be out of work. Basic maintenance is all about fixing things that aren't broken. My philosophy is, '' I can make it work better . ''
After doing this for 33 years I tend to see things most people miss. Not everything and not right away, but I do see them eventually.
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Unfortunately the problem came back...
It seems to start when driving at high speed, then the spluttering will gradually get worse until stopping and restarting the car.
I still feel the issue is ignition related but if it was timing then wouldnt the problem always be there?
I changed the condensor and points last year (mb items) but maybe I should change them again just for completeness?
Any ideas?
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Hello jaymanek
Make sure you have the correct coil and ballast resistor or you may be burning out other ignition items.
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see below
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Just a thought but all the parts ive ordered have been for non transistorized ignition.
Mine is a 69 with cast iron distributor, am i correct in thinking this is non transistorized?
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Ok I dont think my car is transistorized as I cant see any control units under the battery and the wire from neg of coil goes to condensor directly.
The new coil I have been supplied says it is 1.8 ohm and the ballast resisitor says it is 0.9 ohm.
This doesnt seem to tie in with any of the figures in the techical manual!
My car is a 1969 euro car.
From what I can see I should have a coil that has 0.4 ohm resistance and a ballast that has 1.8 ohm.
However the ballast was supplied by Mercedes and the only other one they list is the one for transistorized systems which i believe is a 0.6 ohm.
HELP! What should I have.?
Im wondering that i may have too low resistance which is giving the condensor a tough time so is causing the misfiring under load I am experiencing. Or am i on the wrong tracks?
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Hello,
Sounds like your coil calls for the 1.8 ohm ballast resistor. Change your ballast resistor, ignition points and condensor and the problem should go away for good unless the coil is damaged also.
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Hi All; I too had a similer issue.. Sara Jane would run 15 mins and quit. If i hit the coil with 12v it would run till i took the 12v jumper off and stall put it on again and wold restart..I examined the coil to find it cracked accross the top and was leaking oil from it. I ordered a non resistor coil for $15.bucks from Rock auto, installed it and all is well runs better than ever..I also rebuilt the WRD and now doesnt quite shut all the way but only very light suction at the filter port.. Had an issuer with the inj. pistons - frozen and that was my first fix - watching Joe's posting of recent help.. I also had an inop rack solinoid: But I called H&R and Hans a very willing to help and nice man advised me to tweek the black bakelite rear cover slightly and peen connections and i got luckly it appear to be working again.. She start well & Idles in cold run at about 1100 for 5minute warmup and then drops to my setting of 700 rpm .. couldnt be better.. Regards & thanks all for your help and convidence to geter done.. Clem Beauchemin in CT. PS had a great weekend in ME at Gernold's Shop..
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Diagnostics is a science all to itself. One that can take a while to learn and becomes much harder the more the models of cars you work on. If you only work on one type of car, you can get pretty good at figuring things out.
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Today have changed:
Ballast resistor - 1.8 ohm
Points
Condensor
I think my ignition system is all new now! Dwell angle set at 38 degrees, managed to get it spot on first time!
Fingers crossed.
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Still got the problem, it only seems to do it after thoroughly hot..
Any ideas anyone?
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Hello jaymanek,
Remove the spark plugs and let us know how they look. If the engine is running lean the plugs can short out internally causing a high rpm misfire, especially when the engine is hot.
A fresh set of NGK spark plugs can cure the problem with little expense.
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...and that would be NGK BP6ES I believe...that's what I've got in mine, a '69.
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Hi,
Plugs are all new, I got them from Mercedes to avoid the resistor plugs issue. Leads etc all new too.
Went for another long drive this morning and still the same..the car just gets bogged down after driving around 4-5 miles at speed and when the revs fall, it will just cut out...
The issue seems to build up over a couple of miles, i.e. there will be some intermittent spluttering which gets worse until the car misfires badly and has no power.
A small rest and all is fine again for a little while.
I listened to the fuel pump and that seems to be buzzing away as it should.
Its got to be something simple!?
I have disconnected the distributor advance hose to see if that makes any difference but havent had chance to drive it far enough yet.
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Hi Jay,
If the new plugs you obtained from Mercedes are not NGK BP6ES then you should change them, I had misfire problems some time ago which turned out to be plug related and the only reliable fix for me was to use NGK. I found the worst culprits to be Bosch and Champion plugs which broke down very easily and quickly in my engine. I think most people here would recommend NGK.
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I will try them but I cant the the relationship with heat?
The car runs super strong until.... well until it doesnt!
I have ordered some NGK BP6ES but got to be a long shot.
I am now wondering if there may be a relationship/issue with the WRD?
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Hello Jay,
How about sediment in the fuel tank? Top off the fuel and see if it helps. If the entrance to the flower pot, in the tank, becomes clogged with sediment, the engine will starve for fuel after a short time. If let to rest, it will start and run again for a while. Topping the fuel level allows the fuel to run over the top rim of the "flower pot" and will allow the engine to run without fuel starvation.
Not much chance that the WRD is the culprit. Check it by seeing if its air intake is open during cold running and closes after warm up.
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Thanks,
The problem occurs even with a full tank... Its definately related to temperature somwhere... whether thats coolant temp or just heat build up, im not sure.
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Sorry if I missed it, but how old are the plug and distributor wires? I once had a '63 Chevy that only misfired when hot. I looked under the hood in the dark on night and could see two of the plug wires arcing to the block.
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Probably way off the wall, but is the battery OK and well connected with clean, tight fittings?
May be OK, as is, at lower temperautures, but with heat, may be not well connected. Just a thought.
Joe
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Hi, something to consider:
Although on very different cars, I have experienced identical symptoms.
An old Ford Sierra and a BMW 2000. The issue in both cases was thought to be ignition but turned out to be condensation in the fuel tank working its way up to the carburator.
When I took the carb apart, I could clearly see water droplets in the float chamber on both of those cars.
I've read quite a bit about fuel tank issues on this forum.
It might be worth checking your fuel filter. Try and remove it without spilling out the fuel. That will give you an opportunity to identify any water droplets.
It wont cost anything, and at the least will eliminate one potential cause.
Cheers
Steve
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Hi All,
The leads are new but I will take a look under the bonnet at night... although its a little difficult at the moment as it doesnt get dark until very very late!
Fuel tank issues did cross my mind... I changed the fuel filter a couple of months ago when I carried out a full service. The fuel filter did have more debris in it than id expect but I know the fuel tank was cleaned just before I purchased the car early last year and so i assumed that this is just left over stuff.
However I just think these sorts of issues would show up consistently at all temps... I dont see the relationship between the car warming up and a potentially clogged or contaminated fuel system?
My car is currently at the bodyshop having the dash repainted (been putting that one off for a long time!) but when its back ill need to spend some time under the bonnet.. it must be something ive disturbed or changed when I did the head rebuild....
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Hello,
I would not rule out fuel yet. If the filter had debris in it, your system still could be clogged. The relationship may not be the engine temperature, but the amount of run time before the engine starves for fuel. The screens in the electric fuel pump or tank screen could be clogged.
I would remove the fuel sender in the trunk and have a look in the tank to see if it is still clean.
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Hi Jay,
If the new plugs you obtained from Mercedes are not NGK BP6ES then you should change them, I had misfire problems some time ago which turned out to be plug related and the only reliable fix for me was to use NGK. I found the worst culprits to be Bosch and Champion plugs which broke down very easily and quickly in my engine. I think most people here would recommend NGK.
I have to agree with that.NGK saved my life! BTW, I had misfiring issues mainly whith warm or hot engine before I changed the plugs.
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NGK Plugs installed, no difference, although the old ones were very sooted up... have now set the co level at idle which was a touch high.
However, opened up the tank and the lining has fallen apart... there were large sections of the lining sat at the bottom of the tank.
Where is the best place in europe to buy a new tank? SLS is my usual supplier who seem to supply them at 400 EUR.
Mercedes are too expensive at £800 GBP + tax.
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Try Roger Edwards Motors in Amersham 01494 766766.
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Hello Jaymanek,
It looks like you are at the root of the problem.
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maybe I hope so...
Ref the tank, Roger Edwards says he uses Dealer parts where possible but he has also used the SLS part. He says the quality is not as good as the original.
I would expect this but I cant justify spending £800 on a hollow metal container so have ordered the SLS unit.
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New tank fitted... Im not convinced it caused my problem...car seems to drive good but the car did give a hint of playing up again once or twice on the drive home - nowhere near as bad though.
Need to go on a longer drive to be sure.
If the problem is still there I think I have to retrace my steps from doing the head rebuild, it just has to be linked as I had no such problems before I did the head gasket.
Would fuel pump timing cause such issues?
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Still having issues but I think I may have cracked it... i hope.
Decided to test the fuel flow and was getting around 1-1.5L per minute. This was at the return at tank.
So decided to remove the fuel pump and take it apart... Well I quickly found that the pump was clogged at its intake, there is a small filter from which i removed so much dirt that I wionder how any fuel got past it at all!
I took the pump apart to clean it out but unfortunately the seals all fell to pieces.
It appears the seals arent available from MB for my short fuel pump?
I put it back together with some other seals I had in an assortment, but the fit isnt perfect and for some reason the pump wont pump any fuel, although the motor is running.
Ill play with it another day again.
I decided to order a new bosch fuel pump... very expensive but I hope it will sort out my problem once and for all.
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I would NOT put any sort of lining in a fuel tank. My rad guy told me that the new fuels disolve that stuff and it makes one hell of a mess. Best to leave it bare and keep if filled with fuel.
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Hello Jay
When the fuel pressure or volume is low, check the screen in the tank, the screen in the intake of the fuel pump and the main fuel filter.
Fuel pressure and volume tests are used to diagnose these problems. If any of the filters or screens become clogged, the fuel pressure or volume will be low. This test is a little work but can save you from replacing a lot of expensive parts.
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Yes thanks, ive now learnt all about the fuel system! Ive replaced the tank, new bosch pump on my desk to be fitted today and new filters will be fitted.
Really hope thats the end of it.
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I would NOT put any sort of lining in a fuel tank. My rad guy told me that the new fuels disolve that stuff and it makes one hell of a mess. Best to leave it bare and keep if filled with fuel.
Yes of course, Dan. But, there are too many people out there that will not come to realize that their fuel tank has reached the end of its useful life, and do not want to spend the money on a replacement. They are expensive, no doubt--and even the repros are not cheap--but what is on this car? But when you have an end of life fuel tank, a replacement is the only permanent solution. I was told that years ago (perhaps to make me feel better about the $1,100 the new one cost at the time) and I don't think anything has changed.
Jaymanek, if you are replacing the fuel pump, ensure you have a new set of mounting studs. Those are not expensive, but if you have not had the pump off before, you may not be able to salvage the old ones. At least one of mine broke; the others were not usable. It's a hard life underneath a car...
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I used a repro tankf rom SLS.. I painted the outside and have wax protected it too...
Didnt touch the inside of course.
Im changing the main bracket, mounts, screws, nuts etc
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Yes of course, Dan. But, there are too many people out there that will not come to realize that their fuel tank has reached the end of its useful life, and do not want to spend the money on a replacement. They are expensive, no doubt--and even the repros are not cheap--but what is on this car? But when you have an end of life fuel tank, a replacement is the only permanent solution. I was told that years ago (perhaps to make me feel better about the $1,100 the new one cost at the time) and I don't think anything has changed.
Jaymanek, if you are replacing the fuel pump, ensure you have a new set of mounting studs. Those are not expensive, but if you have not had the pump off before, you may not be able to salvage the old ones. At least one of mine broke; the others were not usable. It's a hard life underneath a car...
I'm aware of that. However, some may be have an otherwise perfectly useable tank after cleaning and go back to nothing by having it coated inside. Having said that, some people may find that some coatings work just fine, sometimes. Which coatings, used with which fuel, and under what conditions, isn't for me to even begin to guess about.
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Massive difference with new fuel pump!
The car starts on the button now, no cranking at all when hot.
I think that had to be the problem, makes sense... Under load the engine was struggling to draw enough fuel.
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I'm with Joe. Check the color of your plugs. An overly lean mixture will not show itself until all elements of the cold start system have been minimized i.e. the engine is at full operating temp. Good luck, some great advice here.
W113SL
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Thanks but I think its now fixed with the new fuel pump.
I will now need to recheck my idle CO level.